Had protected sex week ago. having brown/ red discharge with odor. period went off around 7th. what can it be?

By protected do you: mean protected from conception or infection? At age 46, it is common to have fluctuations in hormone levels that can lead to spotting between periods. But the odor makes me a little more concerned this could be an infection...contraception wouldn't impact this, but use of condom should be relatively effective. I think you would be best served to see your Doc for evaluation/diagnosis. Good wishes:)